In Sql Server there is a database Report Server.  The Execution Log is a
table in that database.

SELECT      ExecutionLog.UserName, ExecutionLog.Parameters, Catalog.Name,
ExecutionLog.TimeStart, ExecutionLog.TimeEnd,
                     ExecutionLog.TimeDataRetrieval, ExecutionLog.Status
FROM         Catalog (nolock) INNER JOIN
                     ExecutionLog (nolock) ON Catalog.ItemID =
ExecutionLog.ReportID
where Executionlog.username <> 'NT AUTHORITY\SYSTEM' ORDER BY  
Executionlog.username, timestart desc

Gives me a list of by usersname and reports.  You can order by
executionlog.timestart to see the latest ones ran.

----
select  name, count(name) as NoTimes
FROM         Catalog (nolock) INNER JOIN
                     ExecutionLog (nolock) ON Catalog.ItemID =
ExecutionLog.ReportID
where Executionlog.username <> 'NT AUTHORITY\SYSTEM'
group by catalog.name
order by count(name) desc
lists reports ran and number of times ran.